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COMPUTER Filed llay 28, 1945 :5 Sheets-Sheet 1 INVENTOR JAMES D. FERGUSON BY QM L H' UL ATTORNEY J. D. FERGUSON COMPUTER Filed Ilay 28, 1945 Aug. 26, 1947.

m u no man 3 Sheets-Sheet 2 INVENTOR JAMES" 0. FERGUSON BYQW W ATTORNEY v Aug. 26, 1947. J. n. FERGUSON 2,426,192

COMPUTER Filed May 28, 1945 3 Sheets-Sheet 3 INVENTOR yAuEsa Fsflausou ATTORNEY Patented Aug. 26, 1947 search Room COMPUTER James D. Ferguson, United States Navy, Arlington, Va.

Application May 28, 1945, Serial No. 596,257

1 Claim. (01. 235-615) (Granted under the actof March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to computing devices, and particularly to improved means for rapidly determining at frequent intervals, or at any desired time, the value of a continuously changing unknown. An important object of the invention is to provide such a device which derives its solutions from a plurality of known factors, one or more of which known factors may be introduced automatically by the normal operative movements of apparatus to which the computations are related.

The invention finds particular utility in the field of fire control, especially in connection with the operation of antiaircraft guns of larger calibers, where it supplies in a rapid and reliable manner the data required for effective fire by the so-called line of sight barrage method, in which a series of rounds with the same fuze setting is fired as quickly as possible from the gun as the target is tracked, all of the rounds being aimed so that they will burst directly along the line of sight from gun to target.

An important object of the invention is to provide a lead angle computing device of very simple and rugged character, which is adapted to be mounted directly on a gun without requiring connection to any remotely located apparatus and which is accordingly adapted to serve as a standby means of fire control for guns normally controlled by automatic directors.

An object related to that last stated is to provide such an extremely simple lead computing device which is adapted to be installed by securing the same directly to the sight yoke or equivalent. part of a gun and which enables accurate local control of the gun, furnishing to the sight setter the data by which he is enabled to deflect the line of sight, by reference to a dial-like chart in a manner analogous to follow the pointer operation, in such wise as constantly to incorporate an eifective lead or sight angle.

The preferred construction herein disclosed is designed for shipboard use against targets employing horizontal or glide bombing tactics and only when the ship itself is attacked. Under such conditions, since the attacking aircraft is moving substantially in a vertical plane through the gun position, variations in the approach angle express themselves in elevation only. Advantage is taken of this fact to simplify the problem and the mechanism by which it is solved.

An additional object of my invention, therefore, is to provide a computer mechanically responsive to gun movement in a vertical plane, which computer will utilize such gun movement automatically to provide fire control data, thereby obviating the necessity of estimation of such data by a member of the gun crew.

For a better understanding of the invention, reference may be had to the following drawings in which Fig. 1 is a front View of a computer designed for use with a 3"/50 cal. gun and represents the preferred embodiment of the present invention;

Figs. 2, 3 and 4 are back, side elevation and plan views, respectively, of the computer shown in Fig. 1, Fig. 3 being partly in section.

Fig. 5 is a graphical representation of a line of sight barrage attainable by means of this invention;

Fig. 6 depicts the computer of the invention mounted on a 3" 50 caliber gun.

Referring specifically to Fig. 6, the computer, shown generally at I0, is rigidly mounted to sight yoke II with the face of the computer in a vertical plane through the bore axis of gun barrel I2 when the latter and pointers sight I 3 are both aimed at a point on the horizon. In repelling an attack by a, horizontal or glide-bombing airplane, the pointer, by operating pointers crank l4, elevates the gun barrel I2 to bring his sight [3 on the target. In so doing, the sight yoke II is also rotated in elevation through a vertical plane causing the computer to operate as hereinafter described. The sight-setter takes his elevation values in minutes of are from the computer and translates them into sight corrections for pointers sight l3. This is done by the sight-setters operation of range-setting crank I5 which raises or lowers sight bar I! through a gear arrangement (not shown); movement of the sight bar causes a raising or lowering of the after end of sight yoke II to which it is rigidly fixed, and the sight yoke in turn imparts its angular displacement to the pointers sight l3.

Referring now to Figs. 1, 2, 3 and 4 for a detailed description of the invention, the computer assembly essentially comprises a quadrantshaped data plate I9 and a pendulum 20, the latter being on a pivot assembly 22 carried by support plate 2|. The dat plate I!) is also mounted on and swingable about the pivot 22 but normally held against such movement and additionally secured by the thumb nut 34 and bolt 33. Mounting bracket 23 is permanently but pivotally fixed at one end to support plate 2| by rivet 25; relative movement between mounting bracket 23 and support plate 2|, for adjustment purposes, is afforded by slot 26 through which protrudes bolt 21 which is fixed to support plate 2|. Wing nut 28 secures the support plate in the desired position relative to the mounting bracket.

Data plate l9 contains a number of values of sight angle in minutes of arc arranged in concentric arcs as shown. These values are calculated mathematically from the various conditions of target motion influencing speed of elevation of the line of sight, Corresponding with each arc of sight angle values is a number-letter designation on the pendulum 20. These are arranged in a vertical series generally designated 39, and will presently be more fully explained. As the data card l9 rotates in response to gun elevation, it sweeps under pendulum 29. Proper values of sight angle are then read from the data plate I9 through window 29 in the pendulum by the sightsetter, who cranks them into pointers sight 1 I3 as previously described.

The above discussion relates only to attacks by horizontal bombers. When the area surrounding the gun position is under attack by a glide bomber, the data plate I9 is rotated on support plate 2| until the index 30 on the latter is opposite the estimated angle of glide on scale 3| of data plate 19. Bolt 33 and knurled knob 34 secure the data plate I9 and support plate 2| in any desired position within the limits of arcuate slot 35. Guides 36, fixed securely to support plate 21, assure substantial juxtaposition of the latter and data plate three successive positions it occupies during a bombing run, is presumed to be a horizontal bomber attacking the ship 38 mountin gun l2 equipp d with the computer of this invention. As target 31 approaches, the gun captain calls out the proper number-letter designation to be used v angles on the computer appearing under the window of the pendulum opposite this designation will furnish the sight-setter with proper sight angles to maintain a line of sight barrage. If, however, a burst appears behind the target, the

'the line of sight, the original letter of the number-designationwas wrong and the gun captain should order a new letter. If the burst was low, a new letter earlier in the alphabet should be ordered; if the burst was high, a new letter later in the alphabet should be used in the'numberletter designation.

While I have described only one embodiment of my invention, namely, a computer designed for use with a specific gun, 3"/50 caliber, having a muzzle velocity of 2700 F. P. S., it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and the appended claim is intended to cover such changes and modifications as fall within the true spirit of the invention.

The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without; the payment of any royalties thereon or therefor.

I claim:

A sight angle computer adapted to be attached to the sight yoke of an elevational gun including a supporting plate adapted to be secured to and be movable with said yoke, a data scale member pivotally carried by and independently adjustable with respect to the plate, means for securing the plate and member together in adjusted position, and an indicia carrying pendulous arm pivoted at the pivot of said scale member and depending vertically over and sweeping said member, its indicia co-operating with the swept data scale to determine a desired sight angle.

JAMES D. FERGUSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 467,256 Markhof Jan. 19, 1892 1,079,794 Muller Nov. 25, 1913 1,716,821 Karnes June 11, 1929 1,498,631 Korlick June 24, 1924 785,434 Poutet Mar. 21, 1905 

